aic7xxx parity error question

[J. Robert von Behren]

Greetings!

I've been seeing some some strange behavior from the aic7xxx driver
under Linux.  The gist is that although I can access my SCSI drive from
DOS (and even boot to the drive), the Linux driver consistently gets
parity errors. 

Here are the details of my setup, and what I've tried so far:

1.  on-board SCSI controller (aic7899)
2.  external SCSI drive (Quantum Atlas 10K)
3.  The SCSI bios sees my drive, and I can successfully boot from it
into DOS
4.  The linux aic7xxx driver gets parity errors upon boot (error message
below)
5.  I've tried two different external SCSI drives, and two different
cables - all permutations give the same results
6.  Disabling the parity checking in the SCSI bios allows the aic7xxx
driver to load, but I just get bogus data back from the device.  (for
example, the partition table is out of whack, mounted file systems that
should have data are empty, etc.)

Performance isn't a concern for this drive - I just need to be able to
mount it and copy a few files around every once in a while.  Is there
some way to force the driver into a "safe but stupid" mode, that is not
likely to have problems?  (Perhaps have all accesses go through the
BIOS, or perhaps dumb down to SCSI 1?)  Are there other things I should
try?

Any suggestions would be most appreciated!!

Best regards,

-Rob von Behren

-----------output from "modprobe aic7xxx"-----------------

SCSI subsystem driver Revision: 1.00
PCI: Enabling device 00:05.1 (0116 -> 0117)
PCI: Found IRQ 10 for device 00:05.1
PCI: Enabling device 00:05.0 (0116 -> 0117)
PCI: Found IRQ 5 for device 00:05.0
scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.1
        <Adaptec aic7899 Ultra160 SCSI adapter>
        aic7899: Ultra160 Wide Channel A, SCSI Id=7, 32/255 SCBs

scsi1 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.1
        <Adaptec aic7899 Ultra160 SCSI adapter>
        aic7899: Ultra160 Wide Channel B, SCSI Id=7, 32/255 SCBs

  Vendor: QUANTUM   Model: ATLAS10K2-TY367L  Rev: DDD6
  Type:   Direct-Access                      ANSI SCSI revision: 03
(scsi0:A:8): 40.000MB/s transfers (20.000MHz, offset 127, 16bit)
(scsi0:A:8:1): parity error detected in Data-in phase. SEQADDR(0x75)
SCSIRATE(0x95)
scsi0:0:8:0: Tagged Queuing enabled.  Depth 253

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